Many conventional task chairs are designed to provide a comfortable sitting position for the sitter, but most of the designs force the sitter's body into unhealthy postures. Lumbar supports are typically attached to the back of the chair, and while the support may be adjustable, it does not provide adequate support for a sitter leaning forward in the chair. This lack of support presents a problem, as many sitters lean forward when engaging in conversation or focusing intently on a task. Even when sitters recline in most chairs, the chairs are still not designed with the proper posture in mind. There is a need for a chair that will encourage proper body posture and provide adequate lumbar support over a variety of sitter positions. By supporting continual movement of the seated person, improved spinal health and worker productivity are achieved.
One feature of the illustrative embodiments is a floating, articulating lumbar support. The support is attached to the frame of the chair by a rocker arm lever, allowing the support to move forward and backwards in response to similar movements by the sitter. The rocker arm may be attached to the back of the seat, at a rear pivot point, by a pair of steel pins. As the sitter fully reclines in the chair, the articulating lumber passes through an opening in the back of the chair, and the sitter's shoulder blades and upper spine are then supported by an auxiliary back. The back and the lumbar support may be constructed of molded glass reinforced nylon, and the rocker arm lever may be constructed of a high grade aluminum alloy, however any suitable materials may be used. A seat cushion layer of the seat may comprise a composite of renewable, blended materials, such as cork, felt, or latex, however any suitable materials may be used.
According to this illustrative embodiment, the chair also has rollers mounted under a movable, contoured seat, allowing the seat to slide smoothly from a forward tilt to a recline position. A front roller provides tracking guidance for the forward portion of the seat, and a floating spring with rollers provides guidance for the rear portion of the seat. Additionally, the rear spring with rollers helps push the seat forward as the sitter moves into a forward tilt position. The seat has a contoured bottom designed to ride smoothly over both sets of rollers. The rollers may be composed of delrin, the seat is composed of glass reinforced nylon, and the spring material is laminated carbon fiber, but any suitable materials may be used.
At the front of the seat is a pivot point where, in one illustrative embodiment, two rocker arms attach to the seat, connecting the seat to a lower torsion spring. The lower torsion spring provides the main resilience for reclining and returning to forward tilt posture. This spring is positioned low, to allow the maximum arc of movement and to lower the center of gravity of a moving user, while providing appropriate leverage for supporting the full range of movement. The pivot point may be machined steel pin, and the lower torsion spring may be made from steel and rubber covered with an aluminum housing, however any suitable pivoting connection may be used and the parts may be made from any suitable material.
The rocker arms of the lumbar support may attach to the rear of a keystone assembly by a lumbar spring assembly. The lumbar spring is a torsion spring, similar to the lower torsion spring, and the lumbar spring provides tension and resilience for the movement of the articulating lumbar support. The spring assembly may be clamped to the rear of the keystone assembly and may be attached with a steel axle to the rocker arms of the articulating lumbar support. The keystone assembly not only connects to the lumbar support, but also connects to the rollers, the lower torsion spring, and to a seat height adjustment lever and height adjustable column. The keystone assembly may be made from cast aluminum, and the lumbar spring may be made from steel and rubber and cased in aluminum, however any suitable materials may be used for construction.
According to another illustrative embodiment, the keystone assembly attaches to a height adjustable column comprised of a gas cylinder and a steel and plastic housing in a preferred embodiment. Adjustments to the seat height can be made by actuating a lever attached to the keystone assembly.
Another feature of one illustrative embodiment is a cast aluminum footrest that curves upward from a center recessed base affixed to the bottom of the central column. The recesses in the base allow clearance for the lower torsion spring when the chair is in a low height position, and consequently the chair can still shift and rotate without contact between the base and the torsion spring. The footrest creates a comfortable place for the sitter to rest his feet without interfering with chair functions. Wheels may also be attached to the end of the footrests to allow the chair to be easily moved about. In one illustrative embodiment, the central base and footrests are made of cast aluminum, however any suitable materials may be used.
The illustrative embodiments also may have several user adjustable features. Two contoured armrests may attach to the contoured seat and may be custom made to fit the individual user. The vertical position of the lumbar support may be raised or lowered to closely match the curves of a sitter's spine. In this embodiment, this adjustment is made by means of a spring button which unlocks the support and allows the user to vertically adjust the height thereof. Additionally, the back and lumbar support may be custom made or selected from a variety of custom sizes, although a standard back and/or lumbar support size may also be used.
These and other features, aspects and advantages of the instant invention will be more clearly understood from the review of the following detailed description of the invention when read in conjunction with the appended drawings, in which: